The heaume or great helm, also called pot helm bucket helm, barrel helm.
Heaume (great helm) is a helmet of the Middle Ages in the context of the crusades and remained in use until the fourteenth century. Knights usually wore the great helm over a mail coif (hood) sometimes in conjunction with a close-fitting iron skull cap known as a cervelliere. The great helm ultimately evolved from the nasal helmet.
Items related: Great Helms, Heaume